An algorithm for retrieving European Remote Sensing Satellite (ERS-1)
scatterometer winds, denoted the Rufenach-Bates-Tosini (RBT) algorithm, is
developed and used to retrieve winds collocated within ± 25 km of buoy
measurements in two oceanic regions, equatorial and midlatitude. An
improvement in the retrieved RBT winds over the European Space Agency (ESA)
winds is due mainly to a geophysical model employing the full available
wind-speed range, including the lightest winds. This model, denoted BMOD5,
is tuned by using the scatterometer and buoy measurements, resulting in two
different models for the midlatitude and equatorial regions. The RBT retrieved
winds exhibit 1) a larger number of solutions (wind vectors) and 2) smaller
biases in wind speed than the ESA wind product. The increase in the number
of retrieved winds is primarily due to lighter winds employed, 0.2 m/s to
18 m/s; whereas, the ESA winds are truncated near 3 m/s. The ESA winds
underestimate the highest winds significantly, by about 20%, and overestimate
the lightest winds. The RBT wind bias is less than a few percent at the
highest winds and a few tenths of a m/s at the lowest winds. Both algoriths
retrieve 180° ambiguous directions almost as often as the true direction.
Regression fits to the winds using the RBT algorithm produce standard
deviations of 1 m/s and 25° near the equator for winds varying from
0.2-10 m/s and 1.2 m/s and 25° at midlatitudes for winds varying from
0.2-18 m/s, provided that the ambiguities are removed.